JP4755094B2 - Polymerization method and related apparatus - Google Patents

Description

  The present invention relates to a polymerization method and related equipment. More particularly, the present invention produces polymer material in a fluid bed reactor having a feed distributor and collects spitwad in the feed to the fluid bed reactor and the feed distributor. Alternatively, the present invention relates to a polymerization method including the provision of a spit quad collector that removes the spit quad from the feed. The invention also relates to an apparatus corresponding to such a method.

  Fluidized bed reactors (also referred to herein as “reactors”) are widely used in the industry to produce a variety of products, such as polyethylene or other polyolefins. One of the problems often encountered in the use of these reactors is non-uniform channeling of the feed through the reactor bed leading to partial or rather total bed fluidization failure; A serious failure of composting can result in sheeting or granulation in the bed and / or requiring reactor shut down.

  The channeling problem has been improved by the use of feed distributors. U.S. Pat. Nos. 5,037,036 and 1,200 detail a feed distributor known in the art.

  One of the disadvantages of the feed distributor is the tendency for solids formed in the reactor and / or recycle loop or introduced separately therein to clog them. As a result of the above, non-uniform channeling can then appear in the combined fluidized bed.

  Attempts to solve these drawbacks are disclosed in the following patents. U.S. Patent No. 6,057,031 discloses a deflector plate and screen disposed within a polymerization reactor and below a feed distributor in the description by Rhee et al. In U.S. Patent No. 6,057,836, Raufast discloses a method for removing solids from above a feed distributor. In US Pat. No. 6,057,096, Cooke et al. Disclose a method that substantially eliminates contamination of the distributor plate by removing oligomers from the recycle feed to the fluidized bed reactor.

US Pat. No. 4,933,149 US Pat. No. 5,082,634 US Pat. No. 5,213,768 US Pat. No. 5,126,414

  Despite these attempts, there is a need for a better solution to the channeling and feed distributor clogging problem described above. The present invention is particularly concerned with meeting this need.

  The process according to the invention comprises (a) a fluidized bed reactor having a feed distributor, a recycle loop associated with the fluidized bed reactor and a reactor loop composed of a feed line. Producing the material; and (b) using a spit quad collector to collect or remove spit quad in the feed to the fluidized bed reactor and the combined feed distributor Wherein the spit quad collector is disposed outside the fluidized bed reactor and in the feed line to the fluidized bed reactor and the feed distributor.

The present invention further provides:
(A) a fluidized bed reactor having a feed distributor, a reactor loop composed of a recycle loop and a feed line combined with the fluidized bed reactor, and (b) collecting or feeding spit quads in the feed. Comprising a spit quad collector for removing the spit quad from the product, the spit quad collector being located outside the fluidized bed reactor and in the feed line to the fluidized bed reactor and feed distributor The present invention relates to an apparatus for producing a polymer material.

  The method according to the invention comprises (a) producing a polymer material in a reactor loop comprising a fluidized bed reactor having a feed distributor, a recycle loop associated with the fluidized bed reactor and a feed line; and (B) using a spit quad collector to collect the spit quad in the feed to the fluidized bed reactor and the combined feed distributor, or to remove the spit quad from the feed, A polymerization process in which the Spitquad collector is located outside the fluidized bed reactor and in the feed line to the fluidized bed reactor and the feed distributor.

  In this specification and claims, “polymeric” and “polymer” should be understood broadly to include “oligomeric” and “oligomer”, and at least “trimeric” “Oligomer” and “oligomer” which refer to substances which are “trimeric” or “trimers” are preferred. “Recycling loop” will be understood in the conventional sense, but also includes parts where recycling is mixed with new supplies or other materials, as in 9-1C of FIG.

  In the following specification and claims, a “spitwad” is a solid that can clog at least one opening of a feed distributor. As used herein, “spit quad” includes solid polymeric materials in the form of threads, sheets, lumps or other similar shapes. Spit quads are often formed and / or observed in the polymerization fluidized bed and associated feed recycling loops.

  In the following specification and claims, a spit quad collector collects or removes spit quads in a feed to a fluidized bed reactor having a combined feed distributor. If the spit quad is not collected or removed, it will clog a portion of the feed distributor. For example, the spit quad collector can be a screen, a filter, a strainer, or a combination thereof. The spit quad collector may be of any shape or size, and may be in the form of, for example, a flat plate, a cone, or a bowl. The diameter of the perforations in a spit quad collector made from perforated material can be of any size that substantially reduces the amount of spit quad that clogs the feed distributor. The preferred diameter of the perforations or apertures in a spit quad collector made from perforated material is in the range of about 75 to about 110% of the aperture diameter of the feed distributor. A more preferred range of perforation diameter in a spit quad collector made from perforated material is in the range of about 75 to about 95% of the feed distributor opening diameter.

  The spit quad collector can also be a cyclone or can include a cyclone. Other types of spit quad collectors include other gas-solid separators such as knockout drums or tanks.

The spit quad collector included in the process according to the invention is arranged outside the fluidized bed reactor and in the feed line to the fluidized bed reactor and the combined feed distributor. In the following description and claims, a “feed line” refers to a part of a process equipment, such as heat exchange, in a flow line prior to introduction of a fluidized bed reactor and a combined feed distributor. It refers to the part of the recycle loop that does not involve a compressor or compressor. The supply line also includes a bypass line as illustrated, for example, by the bypass line 12A . Referring specifically to FIG. 1, the feed line to the fluidized bed reactor and the combined feed distributor is after the compressor 3 in FIG. 1 and before the fluidized bed reactor 1 and the feed distributor 8. Part of the recycling loop. If the optional heat exchanger 4 is present in FIG. 1, then the feed lines to the fluidized bed reactor 1 and the feed distributor 8 are connected after the optional heat exchanger 4 and in the fluidized bed. Part of the recycle loop in front of the reactor 1 and the feed distributor 8. For example, in FIG. 1, the spit quad collector 12 is disposed between the heat exchanger 4 and the fluidized bed reactor 1.

  The recycle loop is part of the polymerization process, and unreacted gas (and / or other material that leaves the fluidized bed reactor) leaves the fluidized bed reactor and is returned to the fluidized bed reactor as feedback. In the present invention, the reactor loop is constituted by a recycle loop and a fluidized bed reactor. An example of a recycle loop in the process according to the invention is shown in FIG. 1 between point 1A where unreacted gas leaves the fluidized bed reactor and points 1B and 1C where recycle gas is fed back to the fluidized bed reactor. It is.

  The process of the present invention includes a fluidized bed reactor as described herein comprising a continuous gas phase polymerization reactor, and more specific examples include polyolefins, particularly (at least in part) α-olefin homopolymers or Producing polymeric materials comprising interpolymers such as polyethylene, polypropylene and interpolymers of ethylene or propylene and at least one other olefin (such as one or more olefins having 3 to 16 carbon atoms). Including a reactor. Here, homopolymers of ethylene or propylene and interpolymers of ethylene or propylene and other olefins are included. Interpolymers include interpolymers of ethylene or propylene and at least one other olefin, wherein the ethylene or propylene content is at least about 50% by weight of the total monomers included; Specific examples of other olefins that can produce ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 1-decene, 1-dodecene 1-hexadecene and the like. Non-conjugated dienes and olefins generated in situ in the polymerization medium can also be used in the present invention.

  The method of the present invention includes a method corresponding to the apparatus of the present invention and vice versa.

  The present invention further provides an apparatus for producing a polymer material comprising: (a) a fluidized bed reactor having a feed distributor, a recycle loop associated with the fluidized bed reactor, and a reactor loop comprising a feed line And (b) including a spit quad collector for collecting or removing spitt quads in a feed to a fluidized bed reactor and a connected feed distributor, the spit quad collector Relates to a device arranged outside the fluidized bed reactor and in the feed line to the fluidized bed reactor and the feed distributor.

  The apparatus of the present invention comprises a fluidized bed reactor as described herein, wherein the fluidized bed reactor is a continuous gas phase polymerization reactor, and more specific examples include polyolefins, particularly (at least in part) homopolymers of α-olefins. Polymer materials comprising interpolymers of polymers or interpolymers such as polyethylene, polypropylene and ethylene or propylene and at least one other olefin (such as one or more olefins having 3 to 16 carbon atoms). Including the reactor to be produced. Here, homopolymers of ethylene or propylene and interpolymers of ethylene or propylene and other olefins are included. Interpolymers include interpolymers of ethylene or propylene and at least one other olefin, wherein the ethylene or propylene content is at least about 50% by weight of the total monomers included; Specific examples of other olefins that can produce ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 1-decene, 1-dodecene 1-hexadecene and the like. Non-conjugated dienes and olefins generated in situ in the polymerization medium can also be used in the present invention.

  The apparatus of the present invention includes the apparatus described herein, including more than one spit quad collector disposed in a recycle loop.

  A further aspect of the invention includes a removable spit quad collector that can be removed from the facility while the polymerization process is in operation. In a preferred embodiment, the apparatus of the present invention further includes a bypass line (considering the supply line) surrounding the spit quad collector and, if necessary, another spit quad in such bypass line. Including the device described herein, including a collector.

  The Spit Quad collector is also equipped to remove the Spit Quad from the Spit Quad collector while the Spit Quad collector is still in operation and the polymerization process continues to operate. Would be advantageous. Thus, the apparatus of the present invention is such that the Spit Quad collector is equipped to remove the collected Spit Quad from the Spit Quad collector while the Spit Quad collector is in operation. Including.

  Each element in the reactor loop for the preferred polyethylene process is illustrated in FIG. 1 and includes a reactor 1 and a recycle loop (having a boundary from 1A to 1B or 1C). The recycling loop consists of optional heat exchangers 2 and 4, a compressor 3, an optional fines cyclone 6, an optional fines return injection device (injector) 7, a spit quad collector 12 and an optional It consists of a spit quad collector 12A. The recycle loop preferably has at least one heat exchanger. A feed distributor 8 is located near the bottom of the reactor. An expanded disengaging zone 5 is provided near the top of the reaction vessel to reduce the entrainment of solids in the effluent gas. In the main gas recycler, various mechanisms are used to replenish ethylene, comonomer, hydrogen and inerts. These are illustrated in FIG. 1 as a single combined stream 9 for simplicity. Catalyst injection in prepolymer formation is indicated by stream 10 and polymer powder removal is indicated as stream 11.

  The invention can be further illustrated by the following examples. These examples are included for the purpose of illustration and it will be understood that they are not intended to limit the scope of the invention unless specifically stated otherwise. The titles given in the examples are for convenience only and are not meant to be limiting unless otherwise specified.

General Construction for the Examples The transition metal component of the Ziegler-Natta catalyst used in the following Examples 1-7 was prepared according to Example 1-a of EP-A-0703246. A Ziegler-Natta catalyst was used to produce the prepolymer and was prepared according to Example 1-b of EP-A-0703246. In this way, a prepolymer having a molar ratio of tri-n-octylaluminum (TnOA) to titanium of about 1.0 and about 35.7 g of polyethylene per millimole of titanium was obtained.

  The continuous gas phase polymerization reaction process used in Examples 1 to 7 consisted of a vertical cylinder having a diameter of 5 m and a height of 16 m, and was carried out in a fluidized bed reactor for gas phase polymerization provided with a deceleration chamber on the top. The reactor was equipped with a feed distributor at the bottom. The reactor also had an external line for recycle gas, which connected the top of the deceleration chamber to a point below the feed distributor at the bottom of the reactor. In this process, the recycle gas is the feed to the polymerization reactor and to the feed distributor. The recycle loop was equipped with a compressor for circulating gas (with a protective screen) and a heat exchanger. In particular, a line supplemented with fresh ethylene, 1-hexene, hydrogen and nitrogen (and usually trace amounts of impurities) representing the major components of the gaseous reaction mixture passing through the fluidized bed is fed into the recycle line. . After the compressor and heat exchanger, the gas recycle line is divided into two separate lines, which are then used to introduce the recycle gas directly below the feed distributor at two points opposite to each other. It was. The arrangement of the recycle gas reactor inlet and the design of the gas mixing chamber below the feed distributor are described in US Pat.

  The feed distributor is designed to distribute the fluidizing gas approximately evenly along the diameter of the fluidized bed reactor. The design of the feed distributor is described in US Pat. The feed distributor has openings, and the gas stream introduced directly below the feed distributor is distributed more or less evenly through these openings.

  Above the feed distributor, the reactor is about 80,000-100, prepared linear low density polyethylene powder (interpolymer of ethylene and 1-hexene) with particles having a weight average particle size of about 0.7 mm. Contained a fluidized bed formed by 1,000,000 kg (drawn reactor rear). The gaseous reaction mixture comprises ethylene, 1-hexene, hydrogen, and nitrogen and is about 1.7 ft / sec (52 cm) under a pressure in the range of about 290 psig (2.0 MPa) to about 305 psig (2.2 MPa). / Sec) to about 1.95 ft / sec (59 cm / sec) through the fluidized bed. The polymer product was intermittently removed from the reactor.

The catalyst was intermittently introduced into the reactor. The catalyst contains magnesium, chlorine and titanium, contains about 35.7 g of polyethylene per millimole of titanium, and tri-n-octylaluminum (TnOA) in an amount such that the molar ratio TnOA / Ti is equal to about 1.0. In the above, it is pre-converted into the containing prepolymer as described above. The rate of introduction of this prepolymer form of catalyst into the reactor was adjusted to achieve the desired production rate. During the polymerization reaction, a solution of trimethylammonium (TMA) in n-hexane at a concentration of about 45% by weight was continuously introduced into the recycle loop. The feed rate of TMA is expressed as the molar ratio of TMA to titanium (TMA / Ti) and the feed rate of TMA (moles of TMA per hour) relative to the feed rate of catalyst in prepolymer form (moles of titanium per hour). Number). At the same time, a tetrahydrofuran (THF) solution in n-hexane having a concentration of 10 to 50% by weight was continuously introduced into the recycle loop. The feed rate of THF is expressed as the molar ratio of THF to titanium (THF / Ti), and the feed rate of THF (THF per hour) relative to the feed rate of the catalyst in prepolymer form (moles of titanium per hour). (Mole number) ratio. Dinitrogen monoxide (N ₂ O) was added as a gas to the recycle loop. The N ₂ O flow was adjusted to maintain the concentration of N ₂ O in the gas phase polymerization medium at about 350 parts per million (ppm) by volume.

A chloroform (CHCl ₃ ) solution in n-hexane at a concentration of 2-30% by weight was continuously introduced into the line in order to recycle the gaseous reaction mixture. The feed rate of CHCl _3, the molar ratio of CHCl ₃ to titanium expressed as (CHCl ₃ / Ti), and per feed rate (time CHCl ₃ to the feed rate of the prepolymer of the catalytic (moles of titanium per hour) Of CHCl ₃ ). CHCl ₃ was added to the recycle loop as a solution in n-hexane.

Example 1: 55-day operation without a Spitquad collector (comparative example)
A continuous gas phase polymerization reaction process was operated according to the general configuration described above. After about 55 days, the feed distributor pressure drop increased to the point indicating severe clogging of the feed distributor. At the same time, the other parts of the recycle loop were clogged, both limiting the gas flow and the reactor could only reach a maximum fluidization rate of about 1.6 ft / sec. Under these conditions, the bed began to show unstable behavior and had to be stopped. Visual inspection of the feed distributor revealed that approximately 35% of the openings in the feed distributor were clogged with spit quads larger than the openings in the feed distributor. Clogging of the feed distributor due to these spit quads occurred from the feed side of the feed distributor. The spit quad was removed from the feed distributor by shutting down the reactor, but this resulted in a long shutdown period.

Example 2: 39-day operation without a Spitquad collector (comparative example)
A continuous gas phase polymerization reaction process was operated according to the general configuration described above. After about 39 days, the feed distributor pressure drop increased to a point indicating severe clogging of the feed distributor. At the same time, other parts of the recycle loop were clogged, both limiting the gas flow, and the reactor could only reach a maximum fluidization rate of about 1.55 ft / sec. Under these conditions the floor began to show unstable behavior and had to be stopped. Visual inspection of the feed distributor revealed that approximately 25% of the openings in the feed distributor were clogged with spit quads larger than the openings in the feed distributor. Clogging of the feed distributor due to these spit quads occurred from the feed side of the feed distributor. Spit quads were removed from the feed distributor by shutting down the reactor, which resulted in a long shutdown period.

Example 3: 4-day operation without a Spitquad collector (comparative example)
A continuous gas phase polymerization reaction process was operated according to the general configuration described above. After about 4 days, the pressure drop in the feed distributor increased to a point indicating severe clogging of the feed distributor. Under these conditions the floor began to show unstable behavior and had to be stopped. Visual inspection of the feed distributor revealed that approximately 45% of the openings in the feed distributor were clogged with spit quads larger than the openings in the feed distributor. Clogging of the feed distributor due to these spit quads occurred from the feed side of the feed distributor. The spit quad was removed from the feed distributor by shutting down the reactor; however, a 137 hour shut down period was required to perform this operation.

Example 4: 5-day operation without a Spitquad collector (comparative example)
A continuous gas phase polymerization reaction process was operated according to the general configuration described above. After about 5 days, the pressure drop in the feed distributor increased to a point indicating severe clogging of the feed distributor. Under these conditions the floor began to show unstable behavior and had to be stopped. Visual inspection of the feed distributor revealed that approximately 30% of the openings in the feed distributor were clogged with spit quads larger than the openings in the feed distributor. Clogging of the feed distributor due to these spit quads occurred from the feed side of the feed distributor. The spit quad was removed from the feed distributor by shutting down the reactor, but a 60 hour shut down period was required to perform this operation.

Example 5: 10-day operation without a Spitquad collector (comparative example)
A continuous gas phase polymerization reaction process was operated according to the general configuration described above. After about 10 days, the pressure drop in the feed distributor increased to a point indicating severe clogging of the feed distributor. Under these conditions the floor began to show unstable behavior and had to be stopped. Visual inspection of the feed distributor revealed that approximately 25% of the openings in the feed distributor were clogged with spit quads larger than the openings in the feed distributor. Clogging of the feed distributor due to these spit quads occurred from the feed side of the feed distributor. The spit quad was removed from the feed distributor by shutting down the reactor; a 70 hour shut down period was required to perform this operation.

Example 6: Zigzag drilling of 0.1875 inch diameter, centered on 0.25 inch, in each of two gas recycling loop lines with an inner diameter of 23 inches fed to a polymerization reactor operated for 90 days using a Spitquad collector A scissors made from carbon steel perforated plate having a thickness of 0.078 inch was attached. The scissors are about 99.5 inches long and are fitted with two parts of the pipe used to connect the inlet piping flanges of the reactor to the respective piping flanges of the two gas recycle lines (1 per line). One). A flange made of a 1/8 inch thick steel plate was welded to the inlet end of the rod. When the scissors were inserted into the two piping spools, the steel flanges of the scissors were mounted using appropriate sealing gaskets between the piping flanges that were connected when the spools were in operation. The soot was made in the shape of a truncated cone having an outer diameter of 22.375 inches at the soot inlet and a diameter of 13.75 inches at the gas outlet end of the soot. The heel length was 85 inches. The mechanical integrity of the cage consists of a 1/8 inch thick steel reinforcement ring, a side support on the outside of the cage, and an additional side support made of 3/8 inch steel chevron on the inside of the cage. It was improved by welding. The discharge end of each spear was attached to four equally spaced brackets welded inside a spool of about 99.5 inches in length, at the end of the spear from which recycled gas exits. Thus, a means was provided for separating the polymer spit quad from the recycle gas upstream of the feed distributor.

  In accordance with the above general configuration, the soot (spit quad collector) described here is installed in the supply line to the reactor and the feed distributor, and the continuous gas phase polymerization reaction process is operated for 90 days. did. After 90 days, the feed distributor pressure drop did not increase much, indicating that the feed distributor was not clogged too much.

Example 7: Internal inspection after operation using a spit quad collector A continuous gas phase polymerization reaction process in accordance with the general configuration described above and with a soot (spit quad collector) installed as in Example 6. Drove for 2 days. After two days, the pressure drop in the feed distributor did not increase so much, but the pressure drop in each spit quad collector increased by approximately 4 lb / inch ² . There was no sign of bed instability and the fluidization rate was maintained above 1.8 ft / sec, but the process was stopped to check the feed distributor and soot. Inspection of the feed distributor showed no clogging at all. Examination of the sputum showed that they collected approximately 100 lbs of polymer spit quads, which collected covering approximately 65% of the sputum surface area. This was estimated to be sufficient material to clog more than 8 times 50% of the openings in the feed distributor. The process of cleaning the soot required that the reactor be shut down in about 33 hours. The feed distributor did not need to be cleaned.

  The citations cited herein are hereby incorporated by reference for the purposes for which they are cited, to the extent that they do not conflict with the disclosure herein.

  The ranges given herein are to be understood as the overall values of the included disclosure (including the end of the range) and not just the end of the range.

  Each aspect of the invention provided is intended to be detailed and should not be construed as limiting the claims unless otherwise indicated.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. To do.
FIG. 1 illustrates an embodiment of the method and apparatus of the present invention.

Explanation of symbols

1 Fluidized bed reactor 1A, 1B, 1C Boundary of cycle loop 2 Heat exchanger (optional)
3 Compressor 4 Heat exchanger (optional)
5 Extended separation area 6 Cyclone for fine particles (optional)
7 Fine particle return injection device (optional)
8 Feed distributor 9 Flow of new feed (combination)
10 Injection of new catalyst 11 Extraction of product 12 Spitquad collector 12A Optional bypass collector

Claims (14)

Producing polymer material in a reactor loop comprised of (a) (i) a fluidized bed reactor including a feed distributor and (ii) a recycle loop associated with the fluidized bed reactor; and (b) spit Collecting or removing spit quads from a flow line to the fluidized bed reactor and the combined feed distributor using a quad collector;
The Supittowaddo collector is and outside the fluidized bed reactor, a part of it without recycle loop process device is interposed in the supply line to the fluidised bed reactor, it arranged to have a polymerization process.   The polymerization method according to claim 1, wherein the fluidized bed reactor is a continuous gas phase reactor.   The polymerization method of claim 1, wherein the polymeric material comprises a polyolefin.   The polymerization process according to claim 1, wherein the polymer material is a homopolymer of ethylene or an interpolymer of ethylene and at least one other olefin.   The polymerization method according to claim 1, wherein the spit quad collector includes a screen, a filter, or a strainer. (A) (i) is a fluidized bed reactor and (ii) the fluidized bed reactor combined reactors loop consists recycle loop and (b) a fluidized bed reactor and combined with a feed distributor Comprising a spit quad collector for collecting or removing spit quads in the feed to the feed distributor;
The spit quad collector produces polymer material that is located in the feed line to the fluidized bed reactor that is outside the fluidized bed reactor and is part of a recycle loop that does not involve process equipment Device to do.   The apparatus of claim 6, wherein the fluidized bed reactor is a continuous gas phase reactor.   The apparatus of claim 6, wherein the polymeric material comprises a polyolefin.   The polymerization apparatus of claim 6, wherein the spit quad collector includes a strainer, a filter, a screen, or a combination thereof.   The polymerization apparatus according to claim 6, wherein the spit quad collector includes a cyclone.   The polymerization apparatus according to claim 6, wherein the spit quad collector includes a knockout drum or a tank. The polymerization apparatus of claim 6, further comprising a bypass line surrounding the spit quad collector, and further comprising another spit quad collector in the bypass line.   7. The polymerization apparatus of claim 6, wherein the spit quad collector is equipped to remove spit quads collected from the spit quad collector during operation of the spit quad collector.   The apparatus of claim 6 wherein the polymeric material is a homopolymer of ethylene or an interpolymer of ethylene and at least one other olefin.

Images